Categorical approaches to classification have also dominated psychiatry, in spite of the fact that they often do not fit. Placing a problem into a category requires that the category have strong boundaries, like a box. Categories assume common causal factors for those in the category, and advocates of categories blame fuzzy boundaries on lack of knowledge. In fact, many psychiatric problems area matter of degree. To the extent that the underlying nature of the problem is categorical, a good system requires that the boundaries are defined so they match nature (like cutting "at the joint"). Clinicians have tended to champion this model, preferring to ignore the problem of degree in their diagnostic labels.

Dimensional model

Dimensional models propose a limited number of important attributes, and then describe dysfunction by placing the individual along each dimension to represent the strength of the attribute for that person. Dimensions can be formed in different ways. For example, a dimension can reflect amount of a single attribute or reflect degree between two opposing attributes. Thus, instead of categorizing a child as "conduct disordered," a therapist might rate the child as high on anger/hostility, low on impulse control, etc. Dimensional models are readily available for a variety of problems, especially childhood disorders. However, they are essentially unused by any major diagnostic system

Prototypical model

The prototypical model is most similar to the categorical model in that it uses categories, but it explicitly allows for fuzziness. Basically, classification relies on idealized lists of criteria that tend to co-occur in the group of those so diagnosed. The idealized list defines the prototype, but diagnostic rules require only some subset of the list, thereby explicitly conceding that many will not fit the entire list. The major diagnostic systems of today rely on this fuzzy categorical approach, as well as traditional categorization. With this approach it is possible for two individuals to receive the same diagnosis but not share a single major symptom.

Reliability and Validity

Reliability refers to the reproducibility or consistency of results. Validity refers to the meaning of the diagnosis. That is, is the diagnosis meaningful or accurate?

Reliability

Reliability refers to the reproducibility or consistency of results. For a diagnosis to be reliable, different diagnosticians would have to mostly give the same diagnosis to the same person, and people with similar symptoms would have to be diagnosed the same. A diagnosis must have reasonable reliability before it can be valid (that is, a random diagnosis cannot be useful.)

DSM

Diagnostic and Statistical Manual of Mental Disorders. As such, the manual provides two types of information: a description of diagnostic criteria, and descriptions of other information, including associated features, causal factors, comorbidity, prevalence, and other disorders to which a specific disorder is most like or with which it is confused.

DSM IV approach

I Clinical Disorders.

II Personality Disorders and Mental Retardation.

III General Medical Conditions.

IV Psychosocial and Environmental Problems.

V Global Assessment of Functioning.

Labeling

charges that diagnoses convey limited understanding, that they sometimes imply attributes that do not fit the person, and that they tend to persist and stigmatize the person even after problems have disappeared.

Brief Psychiatric Rating Scale

Behavior rating scale used to assess the severity of patient problem areas such as guilt feelings and preoccumation with health.

Clinical assessment

Systematic evaluation and measurement of psychological, biological and social factors in a person presenting with a possible psychological disorder.

Concurrent validity, Construct validity, Content validity

Concurrent: Condition of testing in which the results from one test correspond to the results of other measures of the same phenomenon

Construct: Degree to which signs and symbols used to categorize a disorder relate to each other while differing from those for other disorders

Content: Degree to which the characteristics of a disorder are a true sample of the phenomenon in question

False negative and false positive.

Negative: Assessment error in which no pathology is noted (ie test results are negative) when it is actually present

Positive: Assessment error in which pathology is reported when it is actually not present.

Interrater reliability

Degree to which two or more observers make the same ratings or measurements

Mental age

Your mental age based on where you scored on intelligent test

Minnesota Multiphasic Personality Inventory (MMPI)

Developed in late 1930's. Empirically derived standardized personality test that provides scales for assessing such abnormal functioning as depression and paranoia. One of the mose widely used and heavily researched assessment instruments

Multiaxial

Categorization system such as in DSM IV, employing several dimensions ore axes, each used for differentiating among the categories.

Nosology

Classification and naming system for medical and psychological phenomena.

Predictive validity

Degree to which an assessment instrument accurately predicts a persons future behavior

Reactivity

Changes in one persons behavior as a result of observing the behavior in another

Standardization

Process of establishing specific norms and requirements for a measurement technique to ensure it is used consistently across measurement occasions. This includes instructions for administering the measure, evaluating its findings, and comparing these to data for large numbers of people.

Stanford-Binet

Early standardized intelligence test designed to identify children who will experience academic difficulties by assessing their attention, perception, reasoning and comprehension